Abstract
The Pliocene Kurobegawa Granitic Pluton, exposed in the Northern Japan Alps, is vertically divided into the lower, the middle and the upper units. Elliptic mafic enclaves occur densely in the most part of the pluton and hardly mixed with the host magma. In chondrite normalized REE patterns for the host granite, the upper part is depleted in LREE and the lower part is enriched in HREE. Modal analyses of accessory minerals suggest that the granitic magma was probably saturated in allanite after the lower unit was formed during fractional crystallization. Assuming a starting melt composition equivalent to the average composition of the middle and the upper unit, the calculated REE patterns of the granite using modal compositions of accessories and their distribution coefficients show that the characteristics of the REE patterns for 40% fractional crystallization are similar to those of the upper granite.
